Ink-jet printer head and ink-jet printer

Abstract

An ink-jet recording head is capable of always performing high-speed recording with high image quality in a stable manner independently of a change in the environmental temperature while an apparatus is in operation. The configurations of a nozzle 7, an ink supply aperture 6, and a pressure generating chamber 2 are set so that an inertance mT and an acoustic resistance rT (the values substantially at a temperature of 20° C.) of the nozzle 7, the ink supply aperture 6, and the pressure generating chamber 2 in an ink-filled state satisfy expressions (1) and (2), respectively:

What is claimed is:  
     
       1. An ink-jet recording head comprising a pressure generating chamber to be filled with ink, pressure generating means for generating a pressure in said pressure generating chamber, an ink supply chamber for supplying the ink to said pressure generating chamber, an ink supply passage for establishing communication between said ink supply chamber and said pressure generating chamber, and a nozzle in communication with said pressure generating chamber, said pressure generating means causing a pressure change to take place in said air pressure generating chamber so as to discharge an ink droplet from said nozzle; 
       wherein the configurations of said nozzle, said ink supply passage, and said pressure generating chamber are set so that a total sum m T  of inertance and a total sum r T  of acoustic resistance (the values at a temperature of general 20° C.) of said nozzle, said ink supply passage, and said pressure generating chamber in an ink-filled state satisfy expressions (1) and (2), respectively:  
       
         
           0<m T <1.9×10 8 [kg/m 4 ]  (1)  
         
       
       
         
           4.0×10 12 <r T <11.0×10 12 [Ns/m 5 ]  (2)  
         
       
     
     
       2. An ink-jet recording head according to  claim 1 , wherein said nozzle has a tapered portion whose diameter gradually increases toward said pressure generating chamber, and the tapering angle of said tapered portion is 10 to 45 degrees. 
     
     
       3. An ink-jet recording head according to  claim 2 , wherein the opening diameter of said nozzle is 25 to 32 μm. 
     
     
       4. An ink-jet recording apparatus comprising said ink-jet recording head according to  claim 2 . 
     
     
       5. An ink-jet recording head according to  claim 1 , wherein said nozzle is composed of a straight portion provided in the vicinity of an opening and a tapered portion that gradually increases toward said pressure generating chamber, and the tapering angle of said tapered portion is 15 to 45 degrees. 
     
     
       6. An ink-jet recording head according to  claim 5 , wherein the opening diameter of said nozzle is 25 to 32 μm. 
     
     
       7. An ink-jet recording apparatus comprising said ink-jet recording head according to  claim 5 . 
     
     
       8. An ink-jet recording head according to  claim 1 , wherein the diameter of said nozzle gradually increases toward said pressure generating chamber, the longitudinal section of said nozzle is shaped into a curve that has a radius substantially equal to the length of said nozzle, and the length of said nozzle is 50 to  100 μm.    
     
     
       9. An ink-jet recording head according to  claim 8 , wherein the opening diameter of said nozzle is 25 to 32 μm. 
     
     
       10. An ink-jet recording apparatus comprising said ink-jet recording head according to  claim 8 . 
     
     
       11. An ink-jet recording head according to  claim 1 , wherein the opening diameter of said nozzle is 25 to 32 μm. 
     
     
       12. An ink-jet recording apparatus comprising said ink-jet recording head according to  claim 11 . 
     
     
       13. An ink-jet recording head according to  claim 1 , wherein said ink supply passage is an ink supply aperture for establishing communication between said ink supply chamber and said pressure generating chamber. 
     
     
       14. An ink-jet recording apparatus comprising said ink-jet recording head according to  claim 6 . 
     
     
       15. An ink-jet recording head according to  claim 1 , wherein a maximum droplet diameter of the ink droplet is set to 38 to 43 μm. 
     
     
       16. An ink-jet recording apparatus comprising said ink-jet recording head according to  claim 15 . 
     
     
       17. An ink-jet recording head according to  claim 1 , wherein said ink-jet recording head employs an ink with its surface tension set to 25 to 35 mN/m. 
     
     
       18. An ink-jet recording head described in  claim 1 , wherein said ink-jet recording head employs an ink having its viscosity set such that the total sum r T  of the acoustic resistance (the value at a temperature of substantially 20° C.) of said nozzle, said ink supply passage, and said pressure generating chamber in an ink-filled state satisfies expression (3): 
       
         
           4.0×10 12 <r T <11.0×10 12 [Ns/m 5 ]  (3)  
         
       
     
     
       19. An ink-jet recording head according to  claim 1 , comprising a laminated plate constructed by bonding a nozzle plate wherein said nozzle has been drilled, a pool plate wherein a space portion of said ink supply chamber is formed, a supply aperture plate wherein said ink supply passage has been drilled, a pressure generating chamber plate wherein a space portion of said pressure generating chamber has been formed, and a vibrating plate constituting a part of said pressure generating means, and a piezoelectric actuator acting other part of said pressure generating means bonded to said laminated plate. 
     
     
       20. An ink-jet recording apparatus comprising said ink-jet recording head according to  claim 1 .